How easy is it to identify and debug Percona XtraDB Cluster replication problem ?

If you are using PXC, you may have already seen in your datadirectory several log files starting with GRA_

Those files correspond to a replication failure. That means the slave thread was not able to apply one transaction. For each of those file, a corresponding warning or error message is present in the mysql error log file.

Those error can also be false positive like a bad DDL statement (DROP a table that doesn’t exists for example) and therefore nothing to worry about. However it’s always recommended to understand what’s is happening.

As the GRA files contain binlog events in ROW format representing the failed transaction this post explains how to proceed.

The first step to be able to analyze your GRA files is to add a binlog header to the file.
You can download one here : …

Recently there have been discussions on several vulnerabilities in MySQL and closely related projects such as MariaDB and Percona Server. Usually we have inherited security fixes from MySQL when we have updated Percona Server to be based off a new Oracle MySQL release. In this case however, Oracle has been incredibly quiet.

We’ve been examining how these affect current Percona Server versions and will shortly be making security releases and more information available (we wish to ensure what we say is correct in regards to Percona Server).

As seems to often be the case, we already had a release in the pipeline – Percona Server 5.5.28-29.2 which contains many bug fixes that affect users (see our release notes). We’re going to still release 5.5.28-29.2 and shortly after we’ll make 5.5.28-29.3 available …

I had a customer recently who needed to reduce their database size on disk quickly without a lot of messy schema redesign and application recoding.  They didn’t want to drop any actual data, and their index usage was fairly high, so we decided to look for unused indexes that could be removed.

Collecting data

It’s quite easy to collect statistics about index usage in Percona Server (and others) using the User Statistics patch.  By enabling ‘userstat_running’, we start to get information in the INFORMATION_SCHEMA.INDEX_STATISTICS table.  This data collection does add some overhead to your running server, but it’s important to leave this running for a good long while to get a good dataset that is representative of as much of your workload as possible.

If you miss collecting index stats while some …

The Web And PHP Magazine just published an article describing Percona XtraDB Cluster written by Liz van Dijk and Kenny Gryp. It is a pretty high-level introduction to the technology, so definitely give it a read if you’ve been wanting to give it a closer look.

Go to their website http://www.webandphp.com and download Issue number 9 for free!

On Monday I will deliver with Seppo Jaakola from Codership a tutorial on Percona XtraDB Cluster (Percona Server + Galera).

Already in London and you don’t know how to consume the hotel’s bandwidth ? If you attend this tutorial, you can download the Virtual Box appliance we will use during the session.

Two versions are available:

• PLUK 2012 Appliance (32-bit)
• PLUK 2012 Appliance (64-bit)

How to test them:

1. Open the downloaded file with Virtual Box
2. Install all 3 machines
…

If you are interested by a great and revolutionary HA solution for MySQL or even if you already have some experience with PXC and/or Galera, I invite you to attend the tutorial I will deliver in Percona Live MySQL Conference London 2012 (PLUK2012), December 3rd : Percona XtraDB Cluster in a nutshell.

Small amount of theory and a lot of exercises and examples to really tame the beast that PXC is !

A Codership engineer will also be present and happy to help me answering your questions.

Note to attendees: please bring your laptop with a recent Virtual Box installed and enough free space to store 3 VMs (+/-2G per VM). As said …

The Percona Toolkit team is happy to announce the release of Percona Toolkit version 2.1.6. This is the sixth stable release in the 2.1 series, and primarily a bug-fix release; We suggest that users upgrade to the latest version of the tools.

The complete list of changes is on the Launchpad milestone for 2.1.6, but here are some highlights the release:

• pt-online-schema-change can now handle column renames
• pt-online-schema-change’s DELETE trigger no longer fails when altering a primary key
• pt-stalk got a plugin hook interface
• pt-show-grant support for column-level grants
• pt-table-checksum will warn if slaves have a differing binlog_format

Remember that if you need help with Percona Toolkit, we provide flat-fee, unlimited support services with rapid 24×7 response on a …

The idea to use SSD/Flash as a cache is not new, and there are different solutions for this, both OpenSource like L2ARC for ZFS and Flashcache from Facebook, and proprietary, like directCache from Fusion-io.
They all however have some limitations, that’s why I am considering to have L2 cache on a database level, as an extension to InnoDB buffer pool.
Fortunately, there is a project in progress Flash_Cache_For_InnoDB by David which implements this.
David helped us to port his work to the latest Percona Server and you can get it from our launchpad Percona Server 5.5.28 …

Percona is glad to announce the release of Percona XtraBackup 2.0.3 on October 1st, 2012. Downloads are available from our download site here and Percona Software Repositories.

This release is the current GA (Generally Available) stable release in the 2.0 series.

New Features:

• innobackupex now supports new –move-back option that can be used instead of –copy-back in case there isn’t enough free disk space on the server to copy files. As this option removes backup files, it must be used with caution.

Bugs Fixed:

• Symlink for innobackupex-1.5.1 binary has been broken in the previous version of XtraBackup. Bug …

The Percona Toolkit team is happy to announce the release of Percona Toolkit version 2.1.4. This is the fifth stable release in the 2.1 series, and primarily a bug-fix release; We suggest that users upgrade to the latest version of the tools.

The complete list of changes is on the Launchpad milestone for 2.1.4, but here are some highlights the release:

• pt-table-checksum now works with Percona XtraDB Cluster
• The “Version Check” feature, explained at length here.
• –defaults-file is now used when connecting to discovered slaves in pt-table-checksum

All in all, a solid bug-fix release, with the addition of some new features too.

Remember that if you need …